Electrical FaultsOpen Circuit

Current cannot flow as there is a gap in the circuit.

The lamp is off.

Open circuit faults have a higher resistance than expected.

No Fault Open Circuit

break in wire

Short Circuit

Current flows from one wire to the other not reaching the lamp.

The lamp is off.

Short circuit faults have a lower resistance than expected.

Electrical current will always try and follow the path of least resistance.

No Fault Short Circuit

wires touching

The Continuity TesterThe continuity tester is a circuit that is used to detect opencircuit faults.

If the wire is ok the circuit is complete and the lamp lights.

If there is an open circuit fault there is a gap in the circuit and the lamp is off.

Extension LeadsExtension blocks are connected in parallel.

Care must be taken when using an extension block to connect appliances to a socket.

The more appliances connected in parallel the bigger the current flowing through the flex to the extension block.

5 A 5 A2 A 3 A

?? A

to socket

This could cause the flex to overheat.